The Comparison between Novel and Conventional Phase Field Simulation of Ferroelectric Microstructure
碩士 === 臺灣大學 === 應用力學研究所 === 98 === The phase field approach has been employed extensively to study the evolution of microstructure and patterns of domains. There are two phase field models in current literature: conventional and unconventional methods. The main difference between these two approache...
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ndltd-TW-098NTU054990202015-10-13T18:49:38Z http://ndltd.ncl.edu.tw/handle/08743667296760805128 The Comparison between Novel and Conventional Phase Field Simulation of Ferroelectric Microstructure 鐵電微結構於新式與傳統相場模擬之分析比較 Ming-Yin Wu 吳銘胤 碩士 臺灣大學 應用力學研究所 98 The phase field approach has been employed extensively to study the evolution of microstructure and patterns of domains. There are two phase field models in current literature: conventional and unconventional methods. The main difference between these two approaches is the different choice of field variables and the representation of anisotropic energy. Taking the example of ferroelectrics, the conventional phase field method choose the spontaneous polarization as the field variable and it needs an expansion of polynomials at high orders to construct the anisotropic energy density. Instead, the unconventional phase field method adopts the volume fraction of spontaneous polarization as field variable and the construction of anisotropic energy density is simple and concise. In spite of many advantages of using the unconventional phase field approach, this method is not able to handle the multi-phase problem yet, such as the coexistence of rhombohedral of tetragonal phases in the strained epitaxial bismuth ferrite films (BiFeO3). As a result, we choose the conventional phase field model to simulate this phenomenon. The result shows that the existing anisotropic energy density in the conventional phase field models is not able to simulate the problem of phase coexistence due to the saddle structure in the high energy phase. To resolve it, we develop a new anisotropic energy density taking into account the relative minimum structure of both R- and T-phase. The result satisfactorily demonstrates the coexistence of these two phases. Yi-Chung Shu 舒貽忠 2010 學位論文 ; thesis 76 zh-TW |
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碩士 === 臺灣大學 === 應用力學研究所 === 98 === The phase field approach has been employed extensively to study the evolution of microstructure and patterns of domains. There are two phase field models in current literature: conventional and unconventional methods. The main difference between these two approaches is the different choice of field variables and the representation of anisotropic energy. Taking the example of ferroelectrics, the conventional phase field method choose the spontaneous polarization as the field variable and it needs an expansion of polynomials at high orders to construct the anisotropic energy density. Instead, the unconventional phase field method adopts the volume fraction of spontaneous polarization as field variable and the construction of anisotropic energy density is simple and concise. In spite of many advantages of using the unconventional phase field approach, this method is not able to handle the multi-phase problem yet, such as the coexistence of rhombohedral of tetragonal phases in the strained epitaxial bismuth ferrite films (BiFeO3). As a result, we choose the conventional phase field model to simulate this phenomenon. The result shows that the existing anisotropic energy density in the conventional phase field models is not able to simulate the problem of phase coexistence due to the saddle structure in the high energy phase. To resolve it, we develop a new anisotropic energy density taking into account the relative minimum structure of both R- and T-phase. The result satisfactorily demonstrates the coexistence of these two phases.
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author2 |
Yi-Chung Shu |
author_facet |
Yi-Chung Shu Ming-Yin Wu 吳銘胤 |
author |
Ming-Yin Wu 吳銘胤 |
spellingShingle |
Ming-Yin Wu 吳銘胤 The Comparison between Novel and Conventional Phase Field Simulation of Ferroelectric Microstructure |
author_sort |
Ming-Yin Wu |
title |
The Comparison between Novel and Conventional Phase Field Simulation of Ferroelectric Microstructure |
title_short |
The Comparison between Novel and Conventional Phase Field Simulation of Ferroelectric Microstructure |
title_full |
The Comparison between Novel and Conventional Phase Field Simulation of Ferroelectric Microstructure |
title_fullStr |
The Comparison between Novel and Conventional Phase Field Simulation of Ferroelectric Microstructure |
title_full_unstemmed |
The Comparison between Novel and Conventional Phase Field Simulation of Ferroelectric Microstructure |
title_sort |
comparison between novel and conventional phase field simulation of ferroelectric microstructure |
publishDate |
2010 |
url |
http://ndltd.ncl.edu.tw/handle/08743667296760805128 |
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